The unique properties of the servo-controlled magnetic suspension balance originally developed in our laboratories, coupled with its potentially high accuracy, make it suitable for determining densities, viscosities and osmotic pressures of dilute solutions of biomacromolecules. The density and viscosity are measured simultaneously. Another advantage is that all of the measurements are made on small samples of material (approximately 0.2 ml of solution) and without destroying or contaminating the material. The purpose of this work is to further develop and apply the magnetic suspension densimeter-viscometer and the magnetic suspension osmometer. The densities and viscosities potentially can be measured to one part in 10 to the 6th power and 10 to the 4th power respectively and osmotic pressures to from 10 to the minus 4th power to 10 to the minus 5th power cm of water. From the above values together with the concentration, the specific volumes (partial and isopotential), thermodynamic and hydrodynamic molecular volumes, the amount of solvent associated with the molecule both inside and on its surface, the number average molecular weight and the virial coefficient can be derived. In some recent work the variations of the above values have been followed through the course of certain biochemical reactions, i.e., the RNA extrusion from TYMV. The application of the above instruments is being carried out in collaboration with Dr. D.W. Kupke.